U.S. patent number 5,235,586 [Application Number 07/802,207] was granted by the patent office on 1993-08-10 for computer system utilizing compact intelligent disks.
This patent grant is currently assigned to Hewlett-Packard Company. Invention is credited to Scott Feamster, Keith Klemba.
United States Patent |
5,235,586 |
Feamster , et al. |
August 10, 1993 |
**Please see images for:
( Reexamination Certificate ) ** |
Computer system utilizing compact intelligent disks
Abstract
A computer system comprising a removable optical disk having
active circuitry thereon and a disk player is disclosed. The
optical disk includes a storage medium for storing data on one side
and active circuitry for processing the data on the other side. The
disk cartridge includes most of the high speed components of the
computer system, while the disk player includes those components
which are least likely to change over time. By combining the active
circuitry with the data and programs to be processed thereby on a
single disk cartridge, the problems associated with maintaining and
configuring the system are substantially reduced compared to prior
art systems.
Inventors: |
Feamster; Scott (Atherton,
CA), Klemba; Keith (Santa Clara, CA) |
Assignee: |
Hewlett-Packard Company (Palo
Alto, CA)
|
Family
ID: |
25183112 |
Appl.
No.: |
07/802,207 |
Filed: |
December 4, 1991 |
Current U.S.
Class: |
369/100; 369/273;
720/725; G9B/23.003; G9B/7.005; G9B/7.139 |
Current CPC
Class: |
G11B
7/0037 (20130101); G11B 23/0021 (20130101); G11B
7/24 (20130101) |
Current International
Class: |
G11B
7/24 (20060101); G11B 7/24 (20060101); G11B
23/00 (20060101); G11B 23/00 (20060101); G11B
7/00 (20060101); G11B 7/00 (20060101); G11B
7/0037 (20060101); G11B 7/0037 (20060101); G11B
007/24 () |
Field of
Search: |
;369/100,272,273,276,124,54,58,77.2,112,121,13 ;235/492 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
4933926 |
June 1990 |
Tabei et al. |
5051950 |
September 1991 |
Evans, Jr. et al. |
|
Primary Examiner: Dzierzynski; Paul M.
Assistant Examiner: Nguyen; Kiet T.
Attorney, Agent or Firm: Griffin; Roland I. Haggard; Alan
H.
Claims
What is claimed is:
1. A disk cartridge for the storage and processing of information,
said disk cartridge comprising a platter having storage and
processing regions, said storage region comprising an optically
readable medium having digital information stored therein and said
processing region comprising electronic circuitry for processing
said stored information.
2. The disk cartridge of claim 1 further comprising first and
second optical paths for transmitting light pulse to and from,
respectively, said electronic circuitry.
3. The disk cartridge of claim 2 wherein said disk cartridge
further comprises means for mounting said cartridge on a rotating
spindle, said first and second optical paths being positioned on
said cartridge so as to receive and transmit, respectively, light
pulse from light guides in said spindle.
4. The disk cartridge of claim 1 wherein said storage region
further comprises a region of optically readable and writeable
storage media.
5. The disk cartridge of claim 1 wherein said storage region
further comprises a region of magnetically readable and writeable
storage media and wherein said electronic circuitry on said
processing region is positioned such that said magnetically
readable and writeable storage media does not overlie said
electronic circuitry.
6. A computer system comprising a removable disk cartridge and a
disk cartridge player, said removable disk cartridge comprising a
platter having storage and processing regions, said storage region
comprising an optically readable medium having digital information
stored therein and said processing region comprising electronic
circuitry for processing said stored information, said electronic
circuitry comprising means for receiving signals from, and
transmitting signals to, circuitry which is not on said disk
cartridge and first and second power terminals for providing power
to said circuitry, said disk cartridge player comprising:
means coupling power to said first and second power terminals;
means for sending signals to said receiving means;
means for receiving signals from said transmitting means; and
means for illuminating a selected region on said storage region to
enable the reading of information stored in said optically readable
medium.
7. The computer system of claim 6 wherein said illuminating means
comprises means for causing said removable cartridge to rotate on a
spindle under a light source, wherein said means for sending
signals to said receiving means comprises an optically transparent
region in said spindle.
8. The computer system of claim 7 wherein said means for receiving
signals from said transmitting means comprises an optically
transparent region in said spindle.
9. The computer system of claim 6 wherein said illuminating means
further comprises means for reading the information stored in said
optically readable medium, means for generating signals indicative
of said read information, and means for coupling said generated
signals to said sending means.
10. The computer system of claim 6 wherein said removable cartridge
further comprises a writeable storage medium on said storage region
and wherein said disk player further comprises means for writing
said writeable storage medium in response to signals received from
said electronic circuitry.
11. A disk player for actuating a removable disk cartridge
comprising a platter having storage and processing regions, said
storage region comprising an optically readable medium having
digital information stored therein and said processing region
comprising electronic circuitry for processing said stored
information, said electronic circuitry comprising means for
receiving signals from, and transmitting signals to, circuitry
which is not on said disk cartridge, said disk player
comprising:
means coupling power to said removable disk cartridge;
means for sending signals to said removable disk cartridge;
means for receiving signals from said removable disk cartridge;
and
means for illuminating a selected region on said storage region to
enable the reading of information stored in said optically readable
medium.
12. The disk player of claim 11 wherein said illuminating means
comprises means for causing said removable cartridge to rotate on a
spindle under a light source, wherein said means for sending
signals comprises an optically transparent region in said
spindle.
13. The disk player of claim 12 wherein said means for receiving
signals comprises an optically transparent region in said
spindle.
14. The disk player of claim 11 wherein said illuminating means
further comprises means for reading the information stored in said
optically readable medium, means for generating signals indicative
of said read information, and means for coupling said generated
signals to said sending means.
15. The disk player of claim 11 wherein said removable disk
cartridge further comprises a writeable storage medium on said
storage region and wherein said disk player further comprises means
for writing said writeable storage medium in response to signals
received from said electronic circuitry.
Description
FIELD OF THE INVENTION
The present invention relates to computer systems, and more
particularly, to a computer system utilizing disk drives having
active logic contained on the disk cartridge.
BACKGROUND OF THE INVENTION
The continuing improvements in semiconductor fabrication techniques
have made possible the rapid evolution of computer systems. In
addition to providing significantly more powerful computer systems,
the variety of computing hardware and software available to the
average computer user has also increased substantially and is
expected to increase further. While these improvements have greatly
increased the utility of computers, they have made it difficult for
the average user to configure and maintain an up-to-date
system.
The demand for computer technology has shifted from systems
expertise to information expertise. Although users' demands for
computer systems continue to increase, this demand is emphasizing
greater user friendliness and application portability. Users want
to spend more time understanding business information and less time
understanding system complexities. However, system complexity
continues to increase as global markets and competition compel the
management of worldwide information. Thus users find themselves in
a dilemma: they want increasingly diverse information from
increasingly complex computer systems, but these systems require
sophisticated configuration skills that the user does not want to
acquire.
To take advantage of the improvements, the computer user must
update his or her system hardware and software on almost an annual
basis. While some of these updates may be performed by changing a
few components or adding new versions of existing programs, many of
the hardware advances may only be fully utilized by replacing the
entire computer system. The typical individual user computer system
consists of a power supply, a keyboard, a monitor, and a chassis in
which a motherboard is mounted together with one or more peripheral
cards. The motherboard includes the central processing unit,
memory, and bus structure over which the peripheral cards
communicate with the central processing unit. Simple upgrades such
as increasing the memory capacity of the system can be performed by
adding memory chips to sockets on the motherboard and changing the
configuration information to allow this memory to be utilized.
However, major improvements typically require the motherboard to be
replaced. The motherboards are typically configured for some
maximum hardware configuration and operating speed. Major hardware
improvements often require that the motherboard operate at a speed
in excess of that for which it was designed. Furthermore, new
generations of computing hardware often require bus structures that
differ from that on existing motherboards.
The typical computer user is not technically competent to make such
hardware modifications. In fact, the typical computer user has
great difficulty making even minor upgrades such as adding memory
chips to his or her system. As a result, the user often postpones
upgrading his or her system until improvements in technology
justify replacing the entire computer. As a result, the rate at
which new improvements penetrate the computer market is reduced. In
addition, the cost of upgrading a system is increased, because the
entire system including the computer enclosures and power supplies
is replaced instead of merely replacing the components in need of
upgrading.
The process of upgrading computer systems is further complicated by
the need to reload and reconfigure the computer software whenever a
major system upgrade is performed. The process of reconfiguring the
software, while being somewhat less complicated than performing
major system upgrades, also requires a level of competence beyond
that of the typical computer user. The variety of hardware
platforms on which any given piece of software may be required to
operate is too large for software manufacturers to provide software
versions that are optimally tuned for each platform. In addition,
the software manufacturer must assume that the platform may change
during the life of the software, as some users will modify the
hardware with upgrades. To alleviate this problem, software
manufacturers tend to compromise software performance to obtain
systems that are capable of running on a large variety of hardware
configurations without requiring extensive configuration by the end
user.
The advances in semiconductor technology have also made possible
the introduction of special purpose computing hardware that
provides even greater improvements in speed and cost effectiveness
for certain types of problems. For example, parallel processing
techniques may be used to substantially increase the speed of
searching in database operations, provided the database software
has been configured to take advantage of this type of processing.
To fully take advantage of such special purpose hardware, the user
must have access to different computing platforms for different
types of problems. This significantly increases the cost and
complexity of the computer environment. As a result, the potential
advantages of such special purpose hardware have not been realized
in practice.
The extent to which computers have permeated the workplace places a
special burden on individuals who must perform their work in a
number of different geographic locations. The data utilized by
these users can be transported conveniently over network
connections or via portable disk cartridges. Unfortunately,
light-weight portable computing platforms with all the features of
normal desktop computers have not yet become cost effective for
many applications. Hence, the traveling user must often maintain
computers at two or more physical locations. The problems of
assuring that the computer hardware at one location remains
compatible with that at the other locations places an added burden
on such traveling computer users.
Broadly, it is the object of the present invention to provide an
improved computer system.
It is another object of the present invention to simplify the
hardware and software configurations of computer systems.
It is a further object of the present invention to provide a
computer system in which the hardware and software may be upgraded
without requiring the computer user to alter hardware or perform on
site configuration of the hardware or software.
It is yet another object of the present invention to provide a
computer system that may be more easily transported between
physical locations than prior art portable computer systems.
It is a still further object of the present invention to provide a
computer system that provides the user with access to special
purpose computing hardware in those applications that would benefit
from such hardware.
These and other objects of the present invention will become
apparent to those skilled in the art from the following detailed
description of the invention and the accompanying drawings.
SUMMARY OF THE INVENTION
The present invention comprises a computer system having two main
components, a removable disk cartridge and a disk cartridge player.
The removable disk cartridge includes a platter having top and
bottom surfaces. The top surface includes an optically readable
medium having digital information stored therein, and the bottom
surface includes electronic circuitry for processing the stored
information. The electronic circuitry includes interface circuits
for receiving signals from, and transmitting signals to, circuitry
which is not on the disk cartridge. The electronic circuitry is
powered through contacts on the disk cartridge from a source in the
disk player. The disk player includes circuitry for sending signals
to, and receiving signals from, the disk cartridge. The disk player
also includes the read head for reading the information stored on
the top surface of the disk cartridge and circuitry generating
signals indicative of that information and coupling the signals in
question to the disk cartridge. In one embodiment of the present
invention, the signals between the disk cartridge and the circuitry
in the disk player are communicated by generating light pulses that
are transmitted through the spindle on which the disk cartridge
rotates.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is prospective view of a removable cartridge according to
the present invention and the spindle on which it rotates.
FIG. 2 is a block diagram of a computer system according to the
present invention.
FIG. 3 shows an exemplary arrangement of active circuit elements on
the bottom surface of a removable cartridge according to the
present invention.
FIG. 4 is a cross-sectional view of a portion of the hub of a
removable cartridge and the spindle mechanism in one embodiment of
a computer system according to the present invention.
FIG. 5 is a cross-sectional view of a portion of a hub of a
removable cartridge and an alternate spindle mechanism for use in a
computer system according to the present invention.
FIG. 6 is a top view of a removable cartridge according to the
present invention which utilizes two different storage media.
FIG. 7 is a cross-sectional view of an embodiment of the present
invention that utilizes ferro-electric read/write media to
eliminate the need to transmit data stored on the top surface of
the removable cartridge to the bottom surface of the removable
cartridge via signal paths that leave the removable cartridge.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is based on a new form of removable cartridge
disk drive in which the removable cartridge includes both the means
for storing data and hardware for processing the data stored
thereon. The basic features of a computer system according to the
present invention are shown in FIGS. 1 and 2. FIG. 1 is prospective
view of a removable cartridge 10 and the spindle 18 on which it
rotates. Removable cartridge 10 may be viewed as comprising a
platter having a top layer 12 which provides storage space for data
and a bottom layer 14 which includes active circuitry for
processing the data. For the purpose of this discussion, it is to
be understood that "data" may include programs.
Top layer 12 preferably operates in a manner similar to a
conventional optical disk drive. Such a layer includes a storage
medium having properties that may be sensed by a read head 17. The
properties are typically the optical transmissivity or index of
refraction of the storage medium. Read head 17 may also include
circuitry for writing data into the storage medium. Optical storage
media that allow one or more write operations are conventional in
the art, and hence, will not be discussed in detail here.
Bottom layer 14 includes circuitry for processing the data stored
in top layer 12. This circuitry is powered by contacts included in
spindle 18. Typical contacts are shown schematically at 21 and 23.
Information bearing signals are preferably coupled to the circuitry
in question via optical fibers 20 and 22 which transmit and receive
light pulses via spindle 18. The manner in which power and
information signals are coupled to the circuitry on the bottom
layer will be explained in more detail below.
The manner in which a computer system 100 according to the present
invention operates may be more easily understood with reference to
FIG. 2 which is a block diagram of such a computer system. Computer
system 100 comprises a disk player 102 and a removable cartridge
101. Disk player 102 provides the components of computer system 100
that are least likely to be replaced or outmoded. Removable
cartridge 101 includes those components of computer system 100
whose lifetime is relatively short because of improvements in
hardware or software. When system upgrades are needed, removable
cartridge 101 is replaced by another removable cartridge having the
upgrades in question.
Disk player 102 may be used with a variety of removable cartridges.
The different cartridges may have different operating systems
and/or different hardware. Often significant improvements in
computer throughput may be obtained by utilizing a computer
architecture that is specifically optimized for the task at hand.
For example, large database processing systems may benefit from
content addressable memory or other parallel processing techniques.
While graphics workstations may be optimized using a different form
of parallel processor and/or memory configuration. The present
invention allows the user to easily change "computers" when the
particular focus of the user changes while preserving the remainder
of the computer system. This arrangement is significantly more
economical than maintaining a number of separate computer
systems.
In addition, the present invention assures that the software
included on the removable cartridge and the computing hardware are
always properly configured for one another. In the present
invention, the software on the top surface of removable cartridge
101 need function only with the hardware on the bottom surface of
removable cartridge 101. When hardware upgrades are needed, the
entire removable cartridge is replaced with a new removable
cartridge having software specifically configured for the new
hardware. Hence, the computer user is relieved of the burdensome
task of reconfiguring software whenever the user upgrades the
computing hardware.
Another advantage inherent in a computer system according to the
present invention is the portability of the computer system. A user
need only transport the removable cartridge between locations
having disk players according to the present invention. In prior
art systems, a user having an operating system on a transportable
storage medium needs to have computing systems with compatible
hardware at each location. Since these prior art systems include
the components that were most likely to change over time, it is
difficult to guarantee that the systems remain compatible with the
operating system even when the systems were initially setup to be
compatible. Furthermore, if a user needs to use different computing
systems for different aspects of the user's work, the user needs to
have one of each of the different types of computing systems at
each location when using prior art systems. With the present
invention, the user only needs to have one disk player.
In the preferred embodiment of the present invention, the active
circuitry 115 on the bottom surface of removable cartridge 101
includes essentially all of the high-speed computer circuitry such
as the central processing unit, fast memory, and video display
processors including the VRAM associated therewith. The upper
surface of removable cartridge 101 is used to store the operating
system, system data, and a variety of programs for use by the
computer user. The upper surface may also include user data and, as
will be explained in more detail below, storage space which may be
written by the user.
Disk player 102 includes the mechanism for reading data from the
upper surface of removable cartridge 101 and for interfacing the
active circuitry 115 on the bottom surface of removable cartridge
101 to other components of the computer system. The operation of
disk player 101 is coordinated by a controller 120 which provides
the interface between active circuitry 115 and the other components
of computer system 100 such as monitor 124, keyboard 125, and
peripheral interface 122 for controlling other common computer
components connected to bus 119 such as the auxiliary disk storage
shown at 121 and a network interface shown at 123. Controller 120
also operates the read head 117 and provides the communication
between active circuitry 115 and read head 117. As will be
explained in more detail below, this communication is preferably
accomplished by transmitting light signals through spindle 118 on
which removable cartridge 101 rotates when inserted into disk
player 102.
FIG. 3 shows an exemplary arrangement of active circuit elements on
the bottom surface of a removable cartridge 300 according to the
present invention. The circuit elements may be general purpose
computing elements, memory elements, etc. Exemplary circuit
elements are shown schematically at 302 and 304. The circuit
elements are connected via buses such as busses 306-308. The size
and speed of the buses are matched to the circuit elements on
removable cartridge 300. Methods for mounting integrated circuit
chips directly on a planar surface are known to those skilled in
the circuit arts, and hence, will not be discussed in more detail
here. An example of such a mounting technique is provided in
flip-chip solder bump attachment methods to high density substrates
such as multiplayer ceramics or copper polyimide thin films.
The circuit elements preferably receive data from sources remote
from the bottom surface of removable cartridge 300 via an optical
310 which terminates on an interface circuit 313. Similarly, the
circuit elements preferably send data to remote locations via an
optical path 311 with the aid of an interface circuit 312 that
converts the electrical signals on bus 308 to optical signals.
Optical paths 310 and 311 interface with the spindle on which
removable cartridge 300 rotates. The manner in which this interface
is accomplished will be discussed in more detail below. Similarly,
power for the circuit elements on removable cartridge 300 is
received from connections on the spindle. The power connections to
the various buses have been omitted to simplify the drawing.
The manner in which connections are preferably made between the
spindle and the removable cartridge in the present invention may be
more easily understood with reference to FIG. 4 which is a
cross-sectional view of a portion of the hub of a removable
cartridge 402 according to the present invention and the spindle
mechanism on which it rotates. The spindle mechanism includes a
spindle 401 which is connected to an adapter 404 which rotates with
spindle 401. Power is supplied to a set of contacts 406 on the
underside of removable cartridge 402 via a corresponding set of
pins 405 which make contact with said contacts when removable
cartridge 402 is seated in the spindle mechanism and hold-down
flange 403 is engaged. The pins are compressed against the
corresponding contacts by an expansion mechanism 409 which
preferably comprises a compressible material. Power is supplied to
the pins via extensible connections to a set of corresponding
contacts 421 on the underside of adapter 404 which make contact
with a set of stationary contacts 420 on the upper surface of a
stationary section 322. The stationary contacts 420 are preferably
circular rings on which the contacts 421 ride when the spindle
mechanism rotates. Electrically conducting lubricants are normally
used to reduce wear between the stationary and moving contacts.
Such mechanisms are conventional in the electrical mechanical arts,
and hence, will not be described in more detail here.
The optical signals to be inputted to the active circuitry on
removable cartridge 402 are generated by a light source 417 and are
coupled to optical fiber 408 via spindle 401. Spindle 401 is
preferably constructed from a material that is transparent at the
wavelength of the light generated by light source 417. The signals
from light source 417 are injected into the end of spindle 401 via
light pipe 416. The signals in question traverse the length of
spindle 401 and illuminate region 412 at the top of spindle 401. A
portion of the light is captured by optical fiber 408 which
transmits the light in question to an interface circuit included in
the active circuitry on removable cartridge 402. It will be
apparent to those skilled in the art that light source 417 must be
of sufficient intensity to provide a detectable signal after the
losses due to the relatively small solid angle subtended by the end
of optical fiber 408. Alternative coupling methods having lower
light losses will be described below; however, in practice it is
found that the light losses are acceptable.
Signals to be sent from the active circuitry to the controller in
the disk player are converted to optical signals which are
transmitted via optical fiber 407. Light from optical fiber 407
strikes the angled region 412 of spindle 401. The angle of region
412 is chosen such that light striking this region from optical
fiber 407 will be refracted. The angle of the refracted light beam
in spindle 401 is controlled by the angle between region 412 and
the light leaving optical fiber 407 and the index of refraction of
the medium from which spindle 401 is constructed. The angle is
chosen such that the refracted light beam will be totally reflected
by the vertical walls 413 of spindle 401. A portion of the
refracted light is captured by light pipe 414 which applies the
captured light to detector 415.
It should be noted that light loses in the transmission of signals
from removable cartridge 402 to detector 415 are more critical than
light losses between light source 417 and optical fiber 408 because
the power available to generate light signals on removable
cartridge 402 is significantly less than the power available in the
disk player. The need to minimize the power dissipation on
removable cartridge 402 places restraints on the amount of light
that can be generated by the interface circuitry on removable
cartridge 402. Hence, light losses cannot be easily overcome by
increasing the intensity of light generated on removable cartridge
402. The light losses inherent in the arrangement shown in FIG. 4
are much less for a light signal from removable cartridge 402 to
detector 415 than for a light signal from light source 417 to
optical fiber 408 because essentially all of the light leaving
light fiber 307 is captured by spindle 401. Hence, most of light
losses result mainly from the inability of light pipe 414 to
collect all of the light leaving the bottom of spindle 401. These
light losses may be minimized by utilizing light collection
mechanisms at the end of spindle 401. For example, the diameter of
light pipe 414 may be increased so as to collect the majority of
the light leaving the end of spindle 401.
As noted above, the light losses from light source 417 to optical
fiber 408 are normally acceptable. However, in those cases in which
light losses between light source 417 and light fiber 308 are too
large, the configuration shown in FIG. 4 may be replaced by the
configuration shown in FIG. 5. Those components shown in FIG. 5
which serve the same functions as components shown in FIG. 4 are
numbered with similar numbers. The spindle embodiment shown in FIG.
5 differs from that shown in FIG. 4 in that the spindle 510
includes an axially placed light pipe 511 having an end 545 aligned
with light fiber 508 which receives light signals generated by
light source 517. Light source 517 delivers light signals to the
other end of light pipe 511 via light pipe 516. The diameters of
light pipe 511 and optical fiber 508 are selected such that optical
fiber 508 collects most of the light leaving light pipe 511. This
embodiment requires that end 545 and light fiber 508 be aligned
with respect to one another. This alignment may be maintained by
including a detent in removable cartridge 502 which engages a
positioning mechanism in spindle 504 thereby assuring the desired
alignment. Since such alignment mechanisms increase the complexity
and cost of the system, the embodiment shown in FIG. 4 is
preferred.
While the present invention may be utilized with an optical medium
that may only be written once at the time of system integration, it
will be apparent to those skilled in the art that embodiments of
the present invention which include provisions for the user to
write data into the upper surface of the removable cartridge are
also possible. Optically based read/write disks are known to the
arts. Hence, an embodiment of the present invention in which the
removable cartridge utilizes an optically writeable material can
provide a medium in which the user can also write and read data to
be processed by the active circuitry on the removable
cartridge.
In addition, the upper surface of the removable cartridge may be
constructed from a plurality of data storage materials. An
exemplary embodiment of a removable cartridge according to the
present invention which utilizes two different storage media is
shown at FIG. 6. Removable cartridge 600 includes an inner region
602 which is constructed from a medium that may be read and written
using optical methods. This region is accessed by an optical
read/write head 604. Removable cartridge 600 also includes an outer
region 606 which comprises a conventional magnetic material which
is read and written by a magnetic read/write head 608. In this
embodiment, the controller in the disk player controls both the
magnetic and optical read/write heads. Signals from the active
circuitry on the bottom surface of the removable cartridge
determine which read/write heads are utilized. Embodiments having
more than two regions on the removable cartridge will be apparent
to those skilled in the art.
It should be noted that certain types of optically written
read/write disks, as well as conventional magnetic disks, rely on
magnetic fields to write the storage medium. These magnetic fields
can interfere with the operation of the active components on the
underside of the removable cartridge. In embodiments which utilize
such media, the active circuitry can be positioned such that the
circuitry does not underlie these regions or the regions are
separated in a manner which prevents interference from the magnetic
fields in questions. In the preferred embodiments of the present
invention that utilize such multi-media removable cartridges,
optical read/write technologies that avoid the use of magnetic
fields are preferred. Such read/write optical disks are known to
the art. For example, U.S. Pat. No. 5,051,950, discloses a
read/write optical disk technology based on ferro-electric
materials in which no magnetic fields are needed to read or write
the storage medium.
While the embodiments of the present invention described above
utilized a removable cartridge that rotates in the disk player, it
will be apparent to those skilled in the art that embodiments in
which the removable cartridge remains stationary in the disk player
may also be constructed. In such embodiments, the light beam that
is used for reading and/or writing the optical storage medium is
caused to scan the appropriate portion of the upper surface of the
removable cartridge. Such scanning systems are known to those
skilled in the art of "flying spot" scanners. Some of these systems
utilize moving mirrors to deflect a laser beam to the appropriate
location on the surface. The light reflected from the surface is
then collected by a lense which focuses the light on a detector.
Alternatively, cathode ray tubes of various designs may be used in
conjunction with an imaging lense to illuminate the desired area on
the surface of the removable cartridge.
In the preferred embodiments of the present invention, the
removable cartridge is constructed such that the data stored
thereon may also be read in conventional optical disk drives. This
provides a means for accessing the data when a disk player
according to the present invention is not available.
The above-described embodiments of the present invention utilized
an arrangement in which data read from the top surface of the
removable cartridge is transmitted to the active circuitry on the
bottom surface thereof with the aid of a controller via optical
paths through the spindle of the disk player. This arrangement
requires a high speed data path extending from the read head to the
active circuitry on the bottom surface of the removable cartridge.
Such high speed data paths increase the cost of the disk player and
may become obsolete as higher speed disk drives and active
circuitry become available.
An alternative embodiment of a removable cartridge according to the
present invention that does not require an external high speed data
path is shown in FIG. 7 at 700. This embodiment is based on a
read/write optical disk disclosed in U.S. Pat. No. 5,051,950 which
is herein incorporated by reference. Optical disk 700 stores
information by altering the polarization of a ferro-electric layer
702. The polarization is altered by switching a voltage across the
ferro-electric layer at the location corresponding to the bit being
written. This is accomplished by illuminating the location in
question with a laser which causes a photoconductive layer 704 to
become conductive thereby switching a voltage from electrode 708 to
the surface of the ferro-electric layer at the location in
question. The direction of the electric field applied across the
ferro-electric layer determines the direction of polarization of
the ferro-electric material. Hence, a one may be stored by
switching a voltage of V onto electrode 708 and illuminating the
bit location in question, and a zero may be stored by switching a
voltage of -V onto electrode 708 and illuminating the bit location.
Once the polarization of the ferro-electric material has been set,
the direction of polarization at any location can be sensed by
illuminating the location in question and measuring the
photo-current that flows between electrodes 708 and 710. The
direction of flow of the photo-current between these electrodes
indicates the direction of polarization of the storage media at the
location in question.
In this embodiment of the present invention, the circuitry 712 for
operating electrodes 708 and 710 to write data into the
ferro-electric layer 702 are part of the active circuitry on the
bottom surface of the removable cartridge. In addition, this
circuitry includes a sensor for measuring the current flowing
between electrodes 708 and 710 in response to the illumination of a
bit location on the removable cartridge. This circuitry may
directly be connected to the electrodes via conductors from the
bottom surface of the removable cartridge to the top surface such
as those shown at 714. Hence, the need for a high speed optical
signal path from the removable cartridge to the read/write head in
the disk player is avoided. In this embodiment of the present
invention, the disk player need only position the laser over the
appropriate track to enable the active circuitry on the removable
cartridge to read and write data on the top surface of the
removable cartridge. This further reduces the cost of the disk
player and extends the useful lifetime of a disk player, as the
player does not require high speed buses which become obsolete as
technological advances increase the computer processor speeds.
While the above identified embodiments have referred to "top" and
"bottom" surfaces of the removable cartridge as the regions for
storing information and containing the processing circuitry,
respectively, it will be apparent to those skilled in the art that
the roles of the top and bottom surfaces could be reversed. In
addition, it will be apparent to those skilled in the art that
active circuitry could be included on the side of the platter that
includes the optical storage media. Such one sided embodiments are
particularly attractive in large scale integrated circuits in which
the optical storage media may be deposited on the same substrate as
that used to construct the active circuitry. The key feature of the
present invention is the combination of an optical storage region
for storing data and an active circuitry region for processing the
data.
There has been described herein a novel computer system based on a
removable cartridge which includes active circuitry for processing
data stored thereon. Various modifications to the present invention
will become apparent to those skilled in the art from the foregoing
description and accompanying drawings. Accordingly, the present
invention is to be limited solely by the scope of the following
claims.
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